Line-switch.



C. L. GOODRUM.

LINE SWITCH.

APPLICATION man IAN. 20, ms.

Patented Feb. "26, 1918.

yen fo r: C/mr/es L. Good/um. h

UNITED STATES PATEN OFTQE.

CHARLES L. GOODRUM, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC GOlVI- ZPANY, INCORPORATED, OF NEW YORK, N. Y.,. ACORPORATION OF NEW YORK.

LINE-SWITCH.

Specification of Letters Patent.

Patented Feb. 26, 1918.

Application filed January 20, 1916. Serial No. 73,216.

To all whom it may concern:

Be it known that 1, CHARLES L. GooDRUM, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Line- Switches, of which the following is a full, clear, concise, and exact description.

This invention relates to automatic telephone systems, and particularly to means for automatically connecting a calling line to an idle connecting circuit.

The principal object of the present invention resides in the provision of a switch of this character, which employs but a single pair of movable contacts and which is operated by a small number of controlling magnets.

Any desired type of one movement switch may be employed with the present invention. The present circuits, however, were especially designed for a rotating step-by-step switch. The drawing discloses a subscribers individual line switch.

Assuming, now, that the subscriber at substation A initiates a call by removingvhis receiver from its hook, a circuit will be completed from battery through the lower winding of line relay 1, upper armature and.

back contact of cutofi relay 2, over the right side of the subscribers line, through the substation apparatus thereof, back over the left side of the line, lower armature and back contact of relay 2, upper armature and contact of magnet 3 and the upper winding of line relay 1 to ground. Line relay 1 will attract its armatures, completing a circuit from battery through magnet 3, switch motor magnet 4, its individual interrupter 5 and the lower armature and contact of relay 1 to, ground, thus causing the switch brushes 6 and 7 to make one step. The magnet 3 is made slow to release and holds up during the hunting operation of the switch and until 1 the completion of the conversation. This magnet, when energized, actuates a holding pawl to prevent release of the switch, and interrupts, at its upper armature, the lead from the-upper winding of relay 1 to the left side of the line during the testing operation.

In the present system the test contacts of busy connecting circuits will be supplied with battery potential by a circuit extending through magnet 3, relay 2, and the back contact and upper armature of line relay 1 of.

the line switch associated with the connecting circuit at one of its multiples. Thus, while the switch brushes are passing over the terminals of busy trunks, the line relay 1 of the seeking switch will be locked up by a circuit extending from battery through the brush of the switch holding said trunk to the multiple'test terminals of said trunk,

7 will step the brushes 6 and 7from contact to contact until the contacts of an idle trunk are reached. The test contacts of idle trunks may be connected to ground in any usual and well-known manner. This ground maybe connected at the back contact of the releasing magnet of the first selector. switch,

as shown in a Patent 1,245,436, issued November 6, 1917, to Edgar H. Clark. Thus, when the switch engages an idle trunk, no battery potential will be on its test contact, and line relay 1 will retract its armatures and open the circuit for the stepping magnet l, stopping the rotation of the switch. A circuit will also be completed from battery through relays 3 and 2 in series, back contact and upper armature of line relay 1 and test brush 6 to the loweror test contact of the selected trunk, thus causing the trunk to test busy at its multiple contacts. The lower trunk conductor will be connected to ground as previously described, thus causing the energization of relay 2 and continuing the energization of magnet 8. Relay 2, in attracting its armature, opens the circuit for above-mentioned application. Relay 2, in-

deenergizing, disconnects the subscribers line from brushes 6 and 7 andmagnet 3 in deenergizing, allows theswitch to return to its normal position and thereby places it in readiness for another call.

It is obvious that the circuits herein disclosed are equally applicable to a line switch, the motor magnet of which is continuously energized during the movement of the switch, the only modification necessary bcing the omission of the interrupter 5.

By the present structure, the necessity for the third or testwiper on the line switch is avoided, and but a single relay other than the usual line and cut-off relays is required to control the operation of the switch. It will be noted that the line relay is operated: first, to start the switch, and then acts as a test relay to cause theselection of an idle trunk.

What is claimed is:

1. In a telephone system a subsc'rib'ers line, a relay, a group of trunk line terminal contacts. an automatic switch having a brush through which the talking circuit extends, a power magnet for causing said brush to move over said contacts, a circuit for said magnet extending through front contacts of said relay, means for operating said relay when a call is initiated upon said line to close the circuit for said magnet, a circuit through said brush for maintaining said'relay energized while said brush is in engagement with contacts of busy trunks, and means for 'deenergizing said relay to open said magnet circuit when said brush engages the contact of an idle trunk.

2. In a telephone system a subscribers line, a relay, a group of trunk line terminal con'tacts,'an automatic switch having a brush through which the talking circuit extends, a power magnet for causing said brush to move over said contacts, a circuit for said magnet extending through front contacts of said relay, a circuit for said relay including both sides of said line in series closed when a call is initiated upon said line, and a looking circuit for said relay extending through a front contact thereof, said brush and tie contacts of busy trunks.

3. In a telephone system a subscribers line, a relay, a group of trunks having terminal contacts, an automatic switch having a brush through which the talking circuit extends, a power magnet for causing said brush to move over said contacts, a circuit for said magnet extending through front contacts of said relay, a circuit for said relay including both sides of said line in series, means for closing said last circuit when a call is initiated upon said line to operate said relay, a locking circuit for said relay,'extending through a contact thereof, said brush and the terminal contacts of busy trunks and means for deenergizing said relay to open said magnet circuit when said brush engages the contact of an idle trunk.

i. In a telephone system an incoming line comprising a pair of talking conductors, a switch having a pair of brushes in which said conductors terminate, a group of trunk lines having terminal contacts, a power ma gnet for operating said switch to move said brushes over said contacts,a relay, a circuit for said magnet extending through contacts of said relay, means for operating said relay when a call is initiated on said incoming line to close the circuit of said magnet and means responsive to the engagement of one of said brushes with the contact of an idle trunk for causing a reverse operation of said relay to open said magnet circuit.

Ina telephone systeman incoming line including a pair of talking conductors, a switch having a pair of brushes at which said conductors terminate, a group of terminal contacts for out oing lines, a magnet for controlling the operatlon of said switch to move said brushes over said contacts, a relay, a circuit for said magnet extending through front contacts of said relay, a circuit for said relay including both sides of said incoming line in series closed upon the initiation of a call upon said line and a look ing circuit for said relay extending through a front contact thereof, one of said brushes and the contacts-of busy outgoing circuits.

6. In a telephone system a subscribers line, a line relay, a group of trunk lines having terminal contacts, an automatic switch having a movable contact arranged to be included in the talking circuit, a power magnet for causing said movable contact to 'traversesaid terminal contacts, a circuit for said power magnet extending through contacts of said line relay, means to operate said relay when said subscriber initiates a call to start said switch and means responsive to the engagement of said movable contact with the'contact of an idle trunk to reversely operate said relay to stop said switch.

7. In a telephone system a subscribers line, a relay, a group of trunk lines having terminal contacts, an automatic switch having a brush arranged to be included in the talking circuit, a power magnet for causing said brush to move over said contacts, a circuit for said magnet extending through front contacts of said relay, means for energizing said relay when a call is initiated on said line to 'close the circuit for said magnet and means responsive to theengagement of said brush with the contact of an idle trunk for deenergizing said relay to open said magnet circuit.

last circuit when a call is initiated upon:

said line to operate said relay, a locking circuit for said relay extending through a contact thereof, said brush and the terminal contacts of busy trunks, a cut-off relay, and means for de'elnergizing said line relay to open said magnet circuit and close a circuit for said cut-0E relay when said brush engages the contact of an idle trunk.

9. In a telephone system an incoming line including a pair of talking conductors, a switch having a pair of brushes at which said conductors terminate, a group of terminal contacts for outgoing lines, a magnet for causing the movement of said brushes over said contacts, a relay, a circuit for said magnet extending through front contacts of said relay, a circuit for said relay including both sides of said incoming line in series closed upon the initiation of a call upon said line, a locking circuit for said relay extending through a front contact thereof, one of said brushes and the contacts of busy outgoing lines and means responsive to the engagement of one of said brushes with the terminal of an idle outgoing line for interrupting said locking circuit.

In Witness whereof, I hereunto subscribe my name this 19th day of January, A. D.

CHARLES L. GO ODRUM.

copies of this patent may be obtained for five cents each, by addressing the Commissioner of Iatentl,

Washington, D. 0. 

